I edited my post but you did not see it, WD40 or any petrolium product will soak into the structure of the metal, you can not remove it to restore it to food safe condition. When machining parts that will be used with food, the cooling fluid must be food safe, you can not use just any fluid, the same is true with the reworking of the parts.

In real life, my name isWayne P.Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!

The stainless part looked fine, and the gasket was OK - not falling apart of pitted or anything - but I wasn't going to have it torn down to this degree and not replace all the rubber, so I ordered that whole assembly for replacement.

After all the espressoparts.com parts arrived, I did a final cleanup and reassembly. I was hoping to replace the brittle wire/connection protectors, but I didn't want to re-solder the connectors to every lead in the wiring harness, so I was just extra careful removing and replacing the wiring.

The replacement OPV valve part was a little different from the original part, so I have some concerns that maybe a little too much pressure is going to the portafilter; but I know for sure the water is getting up to temp (measured 195-200) and that there is good pressure on the draw. There is very very little outflow from the OPV outflow line though now, in any situation.

I've noticed that the tank needs to be primed more frequently - (before every shot) as if it's running out of the tank when it's not on, but again, maybe this is how it was when it was new too and I just don't remember.

Here is a video of a shot being drawn. I'll add one using a clear glass so you can see the stripes falling through the coffee as it's drawn, but this is pretty clear improvement over no crema at all.

There was about a week when I wondered if the slightly sour aromas during steaming would dissipate; they did soon thereafter.

Some thoughts in closing.

The problem turned out to be a large amount of scale buildup in the boiler not letting the water get up to temp. Additional scale in the OPV meant insufficient pressure and temperature for good extraction. Regular maintenance for the silvia should include descaling and backflushing twice a year - more if you have hard water.

Attempting to descale with CLR by running it through did in fact crack most of the scale off of the interior of the boiler, but it was then trapped in the tank, soaked full of CLR. There was no choice at that point but disassembly. I probably would not run CLR through a machine again because I'm not clear that it doesn't permeate other joints or the plastic/ silicon parts. Maybe I'm just being paranoid.

Soaking parts in vinegar loosened more scale, but a sour aroma on steaming persisted for about a week. Maybe that's the only choice though. It's perfectly fine now.

There was a earlier suggestion that soaking the OPV in WD40 would somehow saturate the brass itself with WD40 and render it tainted. I work for an engineering company that has years of experience designing pumps and piping systems for medical and food service devices. We have engineers on standards bodies who contribute to the authorship and approval of various safety standards in these domains. I can tell you that the suggestion that brass is permeable to Mineral Oil or any other product contained in WD40 is false. Sure, the rubber gasket in the valve itself was a goner, but I had planned on replacing it. The brass housing on the OPV was and is fine.

In closing, I'd like to thank the posters who contributed; like many repairs, the biggest hurdle to cross was having the confidence that the repair attempt wouldn't ruin the equipment. Luckily it was already not working at all, so ruining it more was not really a concern. Thanks for all the pointer to pictures, teardowns, and parts sources.

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